An apparatus extracting information of an object such as a person or a car imaged by a monitoring camera or the like (hereinafter referred to as object information) has been developed. Here, the object refers to an object such as a person, a car, or an animal. Further, the object information is information indicating a position or a shape of the object or information indicating a feature-value of the object. The feature-value of the object is a value indicating a feature such as a face, clothing or the like of a person or a value indicating a feature such as a shape or a color of a car.
An apparatus described in Patent Document 1 detects a change in a viewing direction of a camera using a gyro sensor or a gravity sensor, and changes a frequency of extraction of a feature-value of an image based on the change in the viewing direction of the camera.
An apparatus described in Patent Document 2 extracts a feature-value of a photographing target from an image. The apparatus divides an image into a plurality of areas, and estimates a probability of appearance of a photographing object in each divided area. Also, the apparatus extracts a feature-value of each area after changing a method of representing an image for each area based on the estimated probability.